diff --git a/cmd/mesh-builder/main.go b/cmd/mesh-builder/main.go
index 0eb8215..5928a12 100644
--- a/cmd/mesh-builder/main.go
+++ b/cmd/mesh-builder/main.go
@@ -171,7 +171,7 @@ func answer(ctx context.Context, publisher builder.Publisher, on, workspace stri
 
 	result := link.BuildResult{
 		ID: request.ID, Repository: request.Repository, Path: request.Path,
-		Ref: request.Ref, On: on, Source: request.Source,
+		Ref: request.Ref, On: on, Source: request.Source, DryRun: request.DryRun,
 	}
 	what := "building " + request.Repository
 	if request.Path != "" {
diff --git a/cmd/mesh-controller/build.go b/cmd/mesh-controller/build.go
index 3869e42..6172e39 100644
--- a/cmd/mesh-controller/build.go
+++ b/cmd/mesh-controller/build.go
@@ -592,6 +592,7 @@ func buildAndShow(ctx context.Context, source buildSource, path, ref string, wai
 		ID:         link.NewBuildID(time.Now()),
 		Repository: repository, Path: path, Ref: ref,
 		Held: heldBy(ctx), Seats: seatBases(ctx),
+		DryRun: true,
 	}, wait)
 	if err != nil {
 		return err
diff --git a/cmd/mesh-controller/dry_run_test.go b/cmd/mesh-controller/dry_run_test.go
new file mode 100644
index 0000000..0f08734
--- /dev/null
+++ b/cmd/mesh-controller/dry_run_test.go
@@ -0,0 +1,38 @@
+package main
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/link"
+)
+
+// A dry run's outcome is looked at, never taken in (novox/hq issue 240). The daemon here holds no
+// store at all, so anything that tried to record or register would fail rather than pass quietly.
+func TestADryRunsOutcomeIsTakenInByNothing(t *testing.T) {
+	err := builds{}.Built(t.Context(), link.BuildResult{
+		ID: "build-1", Repository: "ssh://forge/app.git", Ref: "unreviewed", Module: "app", DryRun: true,
+		Manifest: json.RawMessage(`{"module":"app","version":"1"}`),
+	})
+	if err != nil {
+		t.Fatalf("a dry run's outcome was not simply set aside: %v", err)
+	}
+}
+
+// The mark survives the wire both ways: asked as a dry run, answered as one.
+func TestTheDryRunMarkTravelsWithTheBuild(t *testing.T) {
+	raw, _ := json.Marshal(link.BuildRequest{ID: "build-1", Repository: "r", DryRun: true})
+	var asked link.BuildRequest
+	if err := json.Unmarshal(raw, &asked); err != nil || !asked.DryRun {
+		t.Fatalf("the request lost its dry-run mark: %s", raw)
+	}
+	raw, _ = json.Marshal(link.BuildResult{ID: "build-1", DryRun: true})
+	var answered link.BuildResult
+	if err := json.Unmarshal(raw, &answered); err != nil || !answered.DryRun {
+		t.Fatalf("the outcome lost its dry-run mark: %s", raw)
+	}
+	raw, _ = json.Marshal(link.BuildResult{ID: "build-2"})
+	if string(raw) != `{"id":"build-2","repository":"","on":""}` {
+		t.Fatalf("an ordinary outcome carries a dry-run mark: %s", raw)
+	}
+}
diff --git a/cmd/mesh-controller/main.go b/cmd/mesh-controller/main.go
index baa66f4..0f2561f 100644
--- a/cmd/mesh-controller/main.go
+++ b/cmd/mesh-controller/main.go
@@ -253,6 +253,13 @@ func parseAround(set *flag.FlagSet, args []string) ([]string, error) {
 // registered, the same as the waiting command does. Said either way, so the daemon's log tells what
 // became of a build nobody was watching.
 func (b builds) Built(ctx context.Context, result link.BuildResult) error {
+	// **A dry run is looked at, never taken in** (novox/hq issue 240). On 2026-10-04 a dry run of an
+	// unmerged branch was heard here like any build, registered, and its definition reached a machine
+	// before anyone had reviewed it.
+	if result.DryRun {
+		fmt.Printf("%s: a dry run of %s on %s, not taken in\n", result.ID, result.Repository, result.Ref)
+		return nil
+	}
 	manifest, _, err := takeIn(ctx, b.inv, result)
 	// When it was asked, so a plan takes as its outcome only a build asked for it or after it
 	// (novox/hq 04-ISSUES/219). Zero when the id does not say.
diff --git a/internal/link/build.go b/internal/link/build.go
index c7b0500..c866e75 100644
--- a/internal/link/build.go
+++ b/internal/link/build.go
@@ -83,6 +83,10 @@ type BuildRequest struct {
 	// asking and echoed in the outcome, so whoever hears the outcome can register the module with
 	// its true source, whether or not they were the one who asked (novox/hq issue 176).
 	Source *SourceOnSeat `json:"source,omitempty"`
+	// DryRun says the asker wants the outcome to look at and nothing else (novox/hq issue 240): the
+	// builder echoes it, and whoever hears the outcome takes nothing in — no record, no registration,
+	// no plan, nothing a push could send.
+	DryRun bool `json:"dry-run,omitempty"`
 }
 
 // SourceOnSeat names a repository by the seat whose holder serves it and its path there.
@@ -144,6 +148,9 @@ type BuildResult struct {
 
 	// Source is the request's, echoed: the seat form of the repository, for whoever registers.
 	Source *SourceOnSeat `json:"source,omitempty"`
+
+	// DryRun is the request's, echoed: an outcome nobody may take in (novox/hq issue 240).
+	DryRun bool `json:"dry-run,omitempty"`
 }
 
 // ReadRepository is a repository a build read source from besides the module's own, at the branch,